Chorine is a useful raw material for the production of vinyl chloride, phosgene, etc. and it is well known that chlorine is obtained through the oxidization of hydrogen chloride. For example, a process comprising catalytically oxidizing hydrogen chloride with molecular oxygen in the presence of a catalyst to obtain chlorine is known. With this process, a copper base catalyst, which is called a Deacon catalyst, is known to have a good catalytic activity, and various Deacon catalysts comprising copper chloride, potassium chloride and various kinds of compounds as third components are proposed. Besides the Deacon catalysts, processes using chromium oxide or its compound, or a ruthenium oxide or its compound, as a catalyst are also proposed.
However, since the oxidation reaction of hydrogen chloride is an exothermic reaction with 59 kJ/mol-chlorine, it is important to suppress excessive hot spot in a layer packed with the catalyst from the viewpoint of reducing the thermal degradation of the catalyst and maintaining the stability and easiness of operation. Furthermore, the excessive hot spot may induce a runaway reaction in the worst case, or the high temperature gas corrosion of a reactor material may be caused with hydrogen chloride and/or chlorine.
“Catalyst” Vol. 33, No. 1 (1991) describes that, in the reaction of pure hydrogen chloride with pure oxygen in the presence of chromium oxide as a catalyst, it is difficult to remove the hot spot in a fixed bed reaction system, and that it is necessary to use a fluidized bed reactor in a practical apparatus.